biological approach

• assumptions of the biological approach 1


  the biological approach (BA) assumes all psychological behaviours/functions have a biological root at their core.

  To understand human behaviour it is necessary to look at the biological:

  • structures
  • functions
  • processes

  examples of the biological structures, functions and processes include

  • genetics e.g, the role of inherited traits in behaviour.
  • neurotransmitters e.g, the role of serotonin in behaviour.
  • brain structures e.g, the role of the hippocampus in behaviour.
• assumptions of the biological approach 2


  The BA assumes a biological basis for behaviour e.g.

  • memory is a function of the hippocampus
  • depression is the result of irregular neurotransmission
  • aggression is a product of excess testosterone
• the genetic basis of behaviour - biological approach 2

  typically each individual is born with 23 pairs of chromosomes which form the individuals genotype.

  • an individuals chromosomes make up their DNA, which is essentially a set of "instructions" determining individual characteristics.
• the genetic basis of behaviour - biological approach 1


  twin studies compare monozygotic (MZ) and dizygotic (DZ) twins to explore the genetic basis of traits like schizophrenia, IQ or criminality. Researchers look at whether both twins share a trait (e.g, schizophrenia) and use concordance rates to measure agreement. A higher concordance rates suggest a genetic link. For example, McMuffin et a. (1996) found a 46% concordance rate for major depression in MZ twins, compared to 20% in DZ twins, indicating a strong genetic influence, through depression is not purely genetic.
• genotype & phenotype - biological approach 1


  • genotype refers to a persons particular set of genes that make up their DNA
  • it is made up of a combination of alleles that comprise a specific gene.
  • everyone has a unique genotype (apart from MZ twins, who share 100% of their DNA)
  • genotype determines physical characteristics such as eye and natural hair colour.
  • genotype is set/fixed at the point of conception i.e, it can't be changed (unless a specific, spontaneous - and very rare - genetic mutation occurs)
• genotype & phenotype - biological approach 2


  one genotype can produce a wide range of phenotypes depending on the environmental factors present.

  • phenotype refers to the expression of the genotype determined by prevailing external influences and comprises an individuals observable traits e.g,
  • height
  • eye colour
  • hair texture
  • blood type
• environmental factors - biological approach 1


  environmental factors, such as nutrition or exposure to pollutants, can influence a persons phenotype e.g.

  • an individuals genotype will determine how tall they could potentially grow, however, their diet In childhood will determine whether or not they research their maximum height.
• environmental factors - biological approach 2


  a persons genotype may predispose them to specific behaviours e.g, criminality but if specific environmental factors are not in place then this aspect of their genotype may never be expressed in their phenotype.

  • if someone with potential criminality in their genotype has a secure home, good education, a good income and happy relationships they are unlikely to turn to crime.
  • if someone with potential criminality lives in adverse social conditions with attendant mental health issues then they are more likely to turn to crime.
• evaluation of assumptions & the influence of genes - biological approach strength 1


  the biological approach has a range of real-world applications e.g,

  • the success of drug therapies such as SSRI's for the treatment of psychological disorders such as depression and OCD.
  • family history is a reliable predictor of an individual's disease risk due to an understanding of genotype combined with environmental factors.
• evaluation of assumptions & the influence of genes - biological approach strength 2


  twin studies tend to use large samples, e.g,

  • Bouchard et al. (1990) conducted a large-scale study into the heritability of IQ.
  • they collected data on over 1,500 pairs of twins, as well as over 350 adopted and biological siblings.
  • MZ twins reared together showed a correlation of +0.9 ( a hugely significant finding)
  • the large sample size and quantitative data give this study good reliability.
• evaluation of assumptions & the influence of genes - biological approach limitation 1

  arguing that complex human behaviour is a product of genetics alone is an example of biological determinism.

  • this is a simplistic view which ignores the effect of environmental factors in behaviour.
  • people are capable of sophisticated cognitive processing which is not acknowledged by the biological approach.
  • thus limits the external validity of the approach.
• evaluation of assumptions & the influences of genes - biological approach limitation 2


  some well-know twin studies were conducted before the use of DNA testing to determine zygosity.

  • if a pair of twins closely physically resembled each other they might have been labelled MZ when in fact they were DZ.
  • any question as to the veracity of a twin's MZ/DZ status would damage the validity of twin study findings.
• biological structures & neurochemistry - biological approach


  • the biological approach assumes that structure such as the nervous system, the endocrine system and the brain play a key role in human behaviour.
• the nervous system - biological approach 


  the human nervous system comprises

  • central nervous system (CNS):
  • this consists of the brain and spinal cord
  • the CNS receives, sends and responds to sensory information.
  • peripheral nervous systen (PNS):
  • this relays info between the body and the brain
  • this info includes involuntary responses such as breathing and heartbeat as well as sensory info and control of voluntary movement.
• the endocrine system - biological approach 


  • the endocrine system is a chemical messaging system that operate throughout the body.
  • the endocrine system secretes hormones into the bloodstream from differs glands e.g.
  • the pituitary gland is the major endocrine gland (known as the master gland)
  • it makes, stores and releases hormones
  • it instructs other glands to release hormones as well

  examples of hormones include adrenaline (flight or fight), testosterone (male sex hormone), oxytocin (attachment and bonding)
• the brain - biological approach 


  the brain is made up of different regions which are localised to specific tasks e.g.

  • temporal lobe
  • this lobe controls hearing/auditory perception
  • it also controls speech comprehension
  • frontal lobe
  • this lobe is linked to voluntary movement and expressive language.
  • the prefrontal cortex in particular is linked to executive functioning e.g. impulse control.
  • cerebellum
  • this lobe receives info from the spinal cord, sensory systems and other parts of the brain
  • it regulates balance and motor movements
• evolution & behaviour - biological approach 1

  • evolutionary psychology is part of the biological approach to explaining behaviour.
  • the evolutionary approach to explaining behaviour looks at how and why specific human traits have evolved via the process of natural selection e.g.
  • agression
  • evolutionary usefulness to fight off predators and enemies.
  • memory
  • evolutionary usefulness to recall the location of food sources.
  • language
  • evolutionary usefulness to communicate with tribe members
  • mate selection
  • evolutionary usefulness to select a mate who will bear heathy offspring.
• evolution & behaviour - biological approach 2


  due to natural selection, behaviours and traits which are useful for survival and reproduction are retained - and those with are not eventually die out.
• adaptive behaviours - biological approach 1


  adaptive behaviours are those with increase the chances of survival and reproductive success

  • this is why these behaviours are inherited through the generations i.e. how we behave now is the product of causes rooted in the distant past.
  • this is known as the ultimate causes theory of behaviour.
  • genes are the mechanisms which drive evolution
  • any genetically determined behaviour which increases the chances of survival per species will be inherited to future generations.
• adaptive behaviours - biological approach 2

  biological psychologists believe the characteristic of intelligence is adaptive as it enhance human survival.

  • for our ancestors, intelligence manifested as knowing where to find the best food source, understanding weather patterns, fashioning tools, creating transport, negotiating with other tribes etc.
  • intelligence today equates to further education, training, an entrepreneurial drive, a good job.
  • these accomplishments ensure security and abundance of resources i.e. survival and reproductive success.
• evaluation of biological structures & neurochemistry - biological approach strength 1


  research into biological structures uses objective, clinical methods and measures e.g.

  • Zak et al. (2009) measured testosterone levels in blood samples and linked these to a lack of prosocial behaviour.
  • Maguire et al. (2000) used MRI scans to investigate the role of the hippocampus in spatial navigation.
  • the results derived from using these measures can be checked for consistency across time and samples which means they have good reliability.
• evaluation of biological structures & neurochemistry - biological approach strength 2


  there is some compelling evidence inn support of evolution and behaviour

  • Curtis el at. (2004) found that people showed higher levels of disgust for disease-salient images from from neutral images.
  • disgust is an evolution mechanism as it prevents people from ingesting toxic materials.
  • thus, if people have an innate disgust response to rotten, loudly food this lends validity to the idea that human and biologically programmed for survival.
• evaluation of biological structures & neurochemistry - biological approach limitation 1


  the results of research into biological structures, are overly reductionist e.g.

  • levels of testosterone cannot alone account for a lack of prosocial behaviour, other factors such as personality and upbringing could explain this.
  • spatial navigation is also a product of cognition and social factors e.g. having a good memory and being familiar with specific London streets since childhood.
• evaluation of biological structures & neurochemistry - biological approach limitation 2


  some behaviours which are not advantageous to a 21st-century person remain e.g.

  • aggression is, on a practical level, unnecessary for most people.
  • we don't need to fight competitors for food or grapple with dangerous predators daily.
  • being overly aggressive is likely to lead to police involvement and/or alienation from friends and family.
  • thus, an evolutionary explanation of behaviour has limited usefulness.